The present invention relates to a method, apparatus and computer program for applying a predetermined transmission process to the transmission of Internet Protocol (IP) packets of a particular IP flow in an IP network.
The success of Internet Protocol (IP) based networks has created a need for major enhancements in the original best-effort IP service model. In addition to the traditional best-effort applications (email, ftp, etc.) the trend in IP based networks is towards more sophisticated multimedia applications and protocols, including real-time audio and video. In fact, real-time IP applications and protocols already exist, although the current IP standards are not suitable for effectively carrying real-time traffic. To better suit IP based networks for real-time traffic, IP standards are being enhanced with new Quality of Service (QoS) mechanisms. Therefore, it is quite safe to assume that in the near future IP networks will be able to carry different types of traffic over a single packet switched network infrastructure. It can also be assumed that the changes in the IP service model will be reflected in wireless networks, thereby creating a need for development of wireless networks capable of reliably carrying different types of IP applications over the shared radio links.
A conventional IP network 120, as illustrated in FIG. 5, having an IP layer 1201 and a physical layer 1202, interconnects a plurality of hosts 100. FIG. 5 illustrates a representative portion of each host 100. The details of each host 100 are illustrated in FIG. 3. As per FIG. 3 each host 100 includes a RTP layer 1001, an IP session management protocol layer 1002, a UDP layer 1003, a TCP layer 1004, and an IP layer 1005.
As per FIG. 3, if the host 100 is a wireless terminal, then a radio link layer 1011 is provided. Also, as illustrated in FIG. 5, each host 100 can, for example, include a physical layer 1012 which interconnects the host 100 to the IP network 120, via its physical layer 1202. Further, as illustrated in FIG. 3, each host 100 has, for example, Multimedia applications 1006 connected to the RTP layer 1001 and the IP session management protocol layer 1002 via data interface 1007 and a control interface 1008 respectively. Also each host 100 has, for example, legacy applications 1009 connected to the TCP layer via a data interface 1010.
Each host 100 can be any one of a terminal whether wireless or otherwise, a server or any other such apparatus connected to the IP network 120. If the host 100 is a wireless terminal, then a wireless access point is necessary to allow the wireless terminal to communicate with the IP network 120, or any apparatus that operates within IP network 120.
As shown in FIG. 5, IP session management protocols are conducted according to protocols such as H.323, SIP, etc. between hosts so as to setup and release sessions. There is no distinction made between packets that may contain real-time data, or packets that may contain non-real-time data. In the current apparatus, all packets receive best efforts service.
The IP session management protocols currently in use do not depend in any way on the emerging IP-level QoS mechanism. In the currently used IP session management protocols there is no guarantee of available bandwidth or delay experienced by the IP packets. The ideal situation would be to inform the IP and/or link layer QoS mechanisms of the application level IP session in order to provide different priorities for different types of IP sessions. Such a mechanism is particularly important when real-time IP sessions are to be conducted over wireless networks, specifically shared radio links having limited bandwidth.
The problem in transmitting real-time IP traffic over a wireless IP access network is, basically, how to identify and prioritize the IP packets of real-time IP sessions at the IP and radio link layers. In a traditional best-efforts IP packet routing model, all IP packets receive the same treatment despite the type of data the packets are carrying. Thus, the quality of service depends directly on the amount of traffic going through the network. Therefore, when network congestion occurs the quality of service is inevitably poor. To improve the quality of service and to minimize the delay experienced by the IP packets carrying real-time data, some mechanisms for IP packet prioritization are needed.
Since IP is a connectionless network technology, no natural relation between the application level IP sessions and the IP layer routing exists. Thus, there in no standard way to separate IP packets belonging to different IP sessions. Therefore, a mechanism is needed to map the application level IP session management information to QoS capable IP and radio layers.
FIG. 6 illustrates a conventional method of mapping IP QoS control information onto wireless IP transport layers. As shown in FIG. 6, IP applications 200 cause IP communications to be conducted over the IP network between hosts. Particularly, IP communication of IP packets from the IP applications 200 are conducted through IP layer 1003. Further, wireless IP communications of IP packets from the IP applications 200 are conducted through the IP layer 1003 and radio link layer 2001. If the IP communications is control IP packets then such IP communications are conducted through IP session management protocol 1001, wherein control QoS information is transferred between the IP session management protocols 1001 of each of the hosts. In the conventional method of mapping IP QoS information onto wireless IP transport layers there is no standard way to identify IP packets belonging to different types of IP flows. Thus, it is difficult to obtain or set QoS information with respect to different types of IP sessions particularly, wireless IP sessions.
The identification of different types of IP flows, particularly real-time IP flows, is important in wireless IP networks, where limited resources and terminal mobility require effective management of the radio resources. Moreover, there can be several IP session management protocols (H.323, SIP, etc.), which need to be supported in wireless IP networks. It is very difficult to provide a system which offers a QoS interface capable of accommodating all possible IP session management protocols. Various alternative mechanisms have been proposed for identifying different types of IP flows and accommodating different IP session management protocols. However, these alternative mechanisms suffer from various disadvantages.
A first alternative mechanism has been proposed for detecting IP flows by monitoring the IP packet traffic and by applying certain rules to decide that IP packets containing certain header information create an IP flow. The detected IP flows can be given priority over best-effort IP traffic. The problem in this alternative is how to decide on the appropriate QoS for the detected IP flow since no application level signaling information can be used for the decision.
A second alternative mechanism has been proposed for use in third generation (3G) cellular networks where the terminals use Generic Packet Radio System (GPRS) signaling to create PDP contexts to carry IP data. This alternative can be unnecessarily complex for simpler network architectures, such as wireless Local Area Networks (LANs). It is also unclear how well the GPRS protocols are suited for real-time QoS provisioning, since GPRS was originally designed for traditional best-effort IP traffic.
A third alternative mechanism relies on Resource Reservation Protocol (RSVP) signaling that is used for reserving required resources from the IP network. In order to implement this alternative, mapping between the IP session management protocol and the RSVP protocols must be available. This alternative lacks mobility support and probably would require that some modifications be made to the RSVP protocol if applied in wireless IP networks.
A fourth alternative mechanism is disclosed in U.S. Pat. No. 5,912,885 which describes a QoS architecture for wireless Asynchronous Transfer Mode (ATM) networks. In this alternative the concept of an ATM virtual connection is extended over the radio interface. However, although this alternative does support per-user session QoS, it does not address the situation of extending the QoS model so as to be applicable to networks that do not inherently support QoS.
To overcome the above-described disadvantages, a specific QoS interface and QoS management control protocol to identify particular IP flows to which predetermined transmission processes are to be applied applicable to all networks is needed.
The present invention provides an QoS interworking mechanism for mapping IP session management flow information to underlying. IP and link layers of hosts or other such apparatus in an IP network. It should be noted that the present invention is particularly useful in wireless IP networks, wherein the hosts are wireless terminal which communicate with the IP network via other apparatus such as wireless access points over a radio link. However, the present invention can also be applied to other types of networks. One of the features of the present invention is that after the IP session management information is given to the IP and link layers it is possible to identify particular IP flows (e.g., real-time IP flows) and apply a predetermined transmission process to the transmission of the IP packets of the particular IP flows over the IP and link layers. The link layer could, for example, be a radio-link layer. The above feature of the present invention is achieved by defining a generic QoS interface below the IP session management protocols, that together with a QoS management protocol manage the IP network resources.
Therefor according to the above, the present invention provides a method, apparatus and computer program for applying a predetermined transmission process to the transmission of IP packets of a particular IP flow in an IP network, wherein the IP network is connectable to a wireless terminal acting as a host via a radio link and a wireless access point. The present invention is implemented by defining a QoS management protocol in the wireless terminal between an IP session management protocol and each of IP and link layers of the wireless terminal. Further, the present invention is implemented by defining a QoS management protocol in the wireless access point between the QoS management protocol of the wireless terminal and each of IP and link layers of the wireless access point. IP session information is configured in each of the IP and link layers based on IP session management information from the IP session management protocol of the wireless terminal. As a result of such configuration an IP flow between the wireless terminal and the wireless access point is identified as a particular IP flow. Thereafter, a predetermined transmission process can be applied to the transmission of IP packets of the particular IP flow.